Rheostat.



PATENTED OCT. 8l, 1905.

G. B. STEVENSg RHBSTAT.

APPLICATION FILED 0012.12, 1904.

Invenbor;

fwitmesees':

George Stevens I v Mk @Qt-ty engage the forward contact 23 when the handle 3l is drawn upward and to forcev said contact rearward, thereby increasing the friction between engaging portions ofthe contact 23 and the resistance units 10.

The different operative positions of the parts are clearly shown in Fig's. 4 and 5. The upper portion of the cam is provided with a horizontal member 32, which supports a leafspring' 33, which is bulged upward at its center, as clearly shown in Fig'. 1, ag'ainst the under side of an armature 34, to which it is secured at its central point, the ends of the spring being secured to the su pporting member 32. Suitable stops 35 passing' through slots in the outer ends of the spring 33 limit the downward movement of the armature 34 with reference to the sul/)porting member 32. The under side of the supporting member 32 also limits the upward movement of the handle 31 by engaging' with the upper surface of the outer ends of the pins 28, and when so engaging leaves the armature 34 horizontal. rl`he movement of the handle 31 in the downward direction is limited by a suitable stoppin 36, projecting laterally from the cam member and engaging the under side of the forward end of one of the pins 28. A retaining-magnet is also provided at the upper end of the guide-rod 25. This magnet comprises a horseshoe-core 37 and energizing-coils It is housed between the adjacent projecting' portions of the su pporting member 12 and is firmly secured thereto. The outer endsv ot' the core 37 extend outwardly over the upper ends of the resistance units 10 far enough to be engaged on their under side by the upper face of the armature 34. As clearly shown in Figs. 3 and 6. the coils 3S are connected in series betwee'n'one of the contact-blocks 13 and a binding-post 3), said connections being' made by the lead 40. The binding-post 39 is located at any convenient point--as, for cxample, on the supperting-plate 11.

In Fig'. 6 I have shown a rheostat of the type described connected to an electric motor. As there shown, the motor-armature 41 is connected directly between one of the lower terminals of the rheostat and the lead 42 of a suitable supply circuit. rIhe other lower terminal of the rheostat is connected directly to the other lead 43 of the supply-circuit. The field-winding 44 of the motor is connected between the lead 42 and the binding-post 39, as previously indicated, and the coil 38 of the retaining-magnet is connected between said binding-post and the left-hand contactblock 13.

In the operation of the above device the movable member is normally at the lower end of the resistance unit 10, with its contacts 23 in engagement with the dead contact-blocks 15. I/Vhen it is desired to operate the rheostat to cut out resistance, the handle 31 is drawn upward. This has the effect of first forcing' the cam member forward against the forward Contact 23, so as to increase the frictional engagement between the contacts 23 and the exterior of the resistance unit and then carry the same over the exterior surface of said units to progressively cut out the turns of the windings. shown in Fig. 2 is reached the armature 34 is brought against the ends of the core 37 of the retaining-magnet, and the latter being energized will then hold the parts in the position illustrated, thereby leaving' the rheostat with all the resistance eut out. In case of a failure of current in the line or upon the occurrence of other causes which will sutliciently denergize the retaining-magnet the weighted handle 31 will drop and cause the cam member 30 to assume 'the position illustrated in Fig. 5, and thereby reduce the frictional engagement between the movable contacts 23 and the cooperating surfaces of the resistance unit and allow the parts to return to normal position under the action of gravity.

It will be apparent to those skilled in the art that many alterations and modifications may be made in the structure which l have disclosed herein without departing from the spirit and scope of my invention. I therefore do not wish to be limited to the specilic nratter illustrated, but aim to cover by the terms of the appended claims all such alterations and modifications.

That I claim as new, and desire to secure by Letters Patent ot' the United States, is-- 1. A rheostat comprising an elongated resistance unit having exposed contact-surfaces extending' throughout its length, a coperating contact spring-presse .l into engagement with said surface, and means for increasing the pressure of said contact and moving' it longitudinally in response to a pull in one direction.

2. A rheostat comprising a resistance unit consisting' ot' a helical resistance-conductor having its turns continuously forced together to form a rigid structure, a cooperating' contact spring-pressed into engagement therewith, and means for increasing' the pressure of said contact and moving' it longitudinally in response to a pull in one direction.

3. In a rheostat, a movable contact member comprising a longitudinally-movable support, a contact mounted to move laterally on said support, and a cam member operative to give said contact a lateral movement in resgonse to a pull in a longitudinal direction.

4. In a rheostat, a movable contact member comprising' a longitudinally-movable support, a contact mounted to move laterally on said support, a cam for engaging said member to move it laterally, and a weighted member connected with said cam to normally hold it in its non-active position.

In a rheostat, a movable contact member comprising a longitudinally-movable support,

Finally, when the position IIO oppositely-extending spring-contacts mounted to move transversely thereon, a cam pivoted to said support and operative to move the adjacent portions of said contacts toward each other, a weighted handle connected to said cam to normally hold it in non-active positionand stops for limiting the movement of the cam.

6. A rheostat comprising two verticallydisposed resistance units having exposed contact surfaces extending throughout their lengths, an intermediate guide-rod, a contactsupport movable thereon, contacts mounted to move laterally on said support and to engage said contact-surfaces, a cam for moving said contacts laterally to increase their pressure on said surfaces, and a weighted handle connected to said cam to normally hold it in nonactive position.

7. A rheostat comprising two verticallydisposed resistance units having exposed contact surfaces extending throughout their lengths, an intermediate guide-rod, a contactsupport movable thereon, contacts mounted to move laterally on said support and to engage said contact-surfaces, a cam for moving said contacts laterally to increase their pressure on said surfaces, a weighted handle connected to said cam to normally hold it in nonactive position, an armature connected to the upper side of the cam, and a coperating retaining-magnet at the upper end of said guiderod.

8. In a rheostat, a movable contact-carrying member comprising a spring pressed member in frictional engagement with afixed surface, means for increasing the friction between said member and surface and movingl the former over the latter, and means for maintaining the increased frictional engagement between the parts at the end of their movement so as to lock them against return.

9. In a rheostat, a movable contact-carrying member comprising a spring pressed member in frictional engagement with a fixed surface, means for increasing the friction between said member and surface and moving' the former over the latter, and electromagnetic means for maintaining the increased frictional engagement between the parts at the end of their movement so as to lock them against return.

l0. A rheostat comprising an elongated resistance unit having an exposed contact-surface extending throughout its length, a contact-carrying member movable longitudinally thereof, a contact thereon spring-pressed into frictional engagement with said surface, means for increasing the friction between said contact and surface and moving the former over the latter, and means for maintaining the increased frictional engagement between the parts so as to lock them against return.

ll. A rheostat comprising an elongated resistance unit having an exposed contact-surface extending throughout its length, a contact-carrying member movable longitudinally thereof, a Contact thereon spring-pressed into frictional engagement with said surface, means for increasing the friction between said contact and surface and moving the former over the latter, and electromagnetic means for maintaining the increased frictional engagement between the parts so as to lock y them against return.

12. A rheostat comprising one or more resistance units and transversely extending plates rigidly secured to the opposite ends thereof, a guide-rod supported by said plates, and a contact member movable longitudinally of said rod to vary said resistance, said plates being provided with outwardly-turned portions constituting feet upon which `the rheostat is adapted to rest.

13. A rheostat comprising one or more resistance units, transversely-extending plates rigidly secured to the opposite ends of said units and provided with outwardly-turned portions constituting feet, and an opening through one of said feet by which the rheostat may be hung up.

In witness whereof I have hereunto set my hand this 10th day of October, 1904.

GEORGE E. STEVENS.

Vitnesses:

JoHN A. MoMANUs, J r., DUGALD Meli. MoKILLor. 

